1. Field of the Invention
This invention relates generally to the field of roll or cylinder grinding machines and, more particularly, to calipers utilized to measure the diameter of rolls or cylinders received on roll grinding machines.
2. Description of the Prior Art
Metal rolls are commonly used in both the steel and aluminum industries for rolling and shaping a metal piece. After continued use, these rolls become pocked and pitted and therefore must be replaced. Rather than being discarded, the used rolls can be ground on a grinding machine to refinish the roll surface so that the rolls can be reused. Various types of grinding machines are known for grinding cylindrical objects, such as rolling mill work rolls and back-up rolls, to refinish or smooth the rolls. These known devices are generally of two types. In the first type, known as a traveling carriage machine, the roll is rotated in a stationary position and a rotating grinding wheel is moved laterally along the roll to grind the roll to a desired diameter. In the second type, known as a traveling table machine, the rotating grinding wheel is stationary and the spinning roll is passed along the grinding wheel.
The grinding operation is typically a multiple pass operation in which the roll or the grinding wheel moves back and forth for several passes until a desired roll diameter or shape is obtained. As the roll is ground, the diameter or shape of the roll is measured so that the grinding operation can be controlled. In older grinding machines, the roll diameter or shape is measured manually. However, this means that the grinding operation is stopped while the roll is measured. In more recent grinding machines, an automated measurement device, such as a caliper, is mounted on the machine and is used to monitor the roll diameter or shape during grinding.
An example of a known traveling carriage grinding machine is described in U.S. Pat. No. 4,811,524 to Corallo, which is incorporated herein by reference. This known device includes a front bed having a pair of spaced-apart steady rests designed to support the roll to be ground. Rotating devices for rotating the roll are located at the ends of the front bed. A rear bed is located adjacent the front bed. A grinding carriage is moveably mounted on the rear bed and contains a rotatable grinding wheel. The grinding carriage moves back and forth along the rear bed to grind the surface of the roll. A caliper having extended measuring arms which contact the roll is utilized to measure the "after grind" diameter or shape of the roll. The caliper is typically mounted on a measurement carriage moveable along a separate track attached to the front bed. The measurement carriage is moveable independent of the grinding carriage and, therefore, must be controlled independently of the grinding carriage. In a traveling table grinding machine, the grinding carriage would be fixedly mounted on the rear bed while the front bed would be longitudinally moveable to pass the roll back and forth along the grinding wheel. The structure and operation of such known traveling carriages and traveling table grinding devices are readily understood by those of ordinary skill in the art.
A problem with calipers utilized with these known devices is that the measuring arms are mechanically coupled to a motor which is utilized to move the measuring arms toward or away from the roll. When one or more of the measuring arms contacts the roll it is possible, with the mechanical coupling between the measuring arms and the motor, to apply to the measuring arms an excessive force which damages the measuring arms and/or the mechanical coupling between one or both of the measuring arms and the motor.
It is an object of the present invention to overcome the above problems and others by providing a caliper that avoids damaging a measuring arm of the caliper. Still other objects will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.